Asthma is one of the most frequent chronic diseases with a prevalence of up to 10% (Jarvis and Burney, Br. Med. J. 316:607 (1988)). Both genetic and environmental factors contribute to the overall phenotype. Family studies have shown an increased frequency of asthma in first-degree relatives (Marsh, Allergol. Immunopathol. (Madr.) Suppl 9:60 (1981), Townley et al, J. Allergy Clin. Immunol. 77:101 (1986)). Environmental exposure to allergens, pollutants, and viral respiratory infections are important in the development of asthma (Boushey et al, Am. Rev. Respir. Dis. 121:389 (1980), Cookson and Moffat, Hum. Mol. Genet. 9:2359 (2000)). The interaction between the genetic and environmental factors in the pathogenesis of asthma is not fully understood. Asthma is the most common chronic childhood disease in developed nations and carries substantial direct and indirect economic cost (Lenny, Pediatr. Pulmonol. Suppl. 15:13 (1997)). The prevalence of asthma and other allergic diseases has risen over the past 2 decades (McNally, et al, Soc. Sci. Med. 46:729 (1998)) and the cost of treating the disease in United States is approximately US $6 billion per annum (Smith et al, Am. J. Respir. Crit. Care Med. 156:787 (1997)).
In view of the impact of asthma, better methods of identifying children at risk, and of assessing the efficacy of anti-asthma therapeis, would be beneficial.